c7ce03dce1
Summary: Previously we enabled tracking expected state changes during `FinishInitDb()`, as soon as the DB was opened. This meant tracing was enabled during `VerifyDb()`. This cost extra CPU by requiring `DBImpl::trace_mutex_` to be acquired on each read operation. It was unnecessary since we know there are no expected state changes during the `VerifyDb()` phase. So, this PR delays tracking expected state changes until after the `VerifyDb()` phase has completed. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9470 Test Plan: Measured this PR reduced `VerifyDb()` 76% (387 -> 92 seconds) with `-disable_wal=1` (i.e., expected state tracking enabled). - benchmark command: `./db_stress -max_key=100000000 -ops_per_thread=1 -destroy_db_initially=1 -expected_values_dir=/dev/shm/dbstress_expected/ -db=/dev/shm/dbstress/ --clear_column_family_one_in=0 --disable_wal=1 --reopen=0` - without this PR, `VerifyDb()` takes 387 seconds: ``` 2022/01/30-21:43:04 Initializing worker threads Crash-recovery verification passed :) 2022/01/30-21:49:31 Starting database operations ``` - with this PR, `VerifyDb()` takes 92 seconds ``` 2022/01/30-21:59:06 Initializing worker threads Crash-recovery verification passed :) 2022/01/30-22:00:38 Starting database operations ``` Reviewed By: riversand963 Differential Revision: D33884596 Pulled By: ajkr fbshipit-source-id: 5f259de8087de5b0531f088e11297f37ed2f7685 |
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README.md
RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on LevelDB by Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast key-value server, especially suited for storing data on flash drives. It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF) and Space-Amplification-Factor (SAF). It has multi-threaded compactions, making it especially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/main/examples
See the github wiki for more explanation.
The public interface is in include/. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Questions and discussions are welcome on the RocksDB Developers Public Facebook group and email list on Google Groups.
License
RocksDB is dual-licensed under both the GPLv2 (found in the COPYING file in the root directory) and Apache 2.0 License (found in the LICENSE.Apache file in the root directory). You may select, at your option, one of the above-listed licenses.